This invention relates to apparatus for forming an outwardly concave profile on an end wall of a container on a punch moveable towards and away from the apparatus, and more particularly, but not exclusively to the dome forming station on a press forming can bodies.
Dome forming stations are described in U.S. Pat. No. 4,930,330 (WEISHALLA) and U.S. Pat. No. 4,372,143 (ELERT) in which the dome forming apparatus comprises a dome forming pad surrounded by a clamp ring having a profile to receive a can bottom as drawn, and resiliently hold a peripheral portion of the can bottom against a peripheral end wall portion of the advancing punch. Although these doming stations have been used commercially they are vulnerable to wear leading to diminished accuracy of alignment.
WO 89/07021 (ADOLF COORS) describes dome forming apparatus in which a relatively rigidly supported dome forming tool is surrounded by a first sleeve resiliently urged to act on an inner annulus of a can bottom while a second sleeve or holder is resiliently urged against a peripheral portion of the can bottom against the dome forming tool. These prior art forming tools are all vulnerable to sliding wear, a risk made greater as clearances increase to permit ingress of dirt or debris.